Journal of Ocean Engineering and Science

Volume 1, Issue 4

(3)Prediction of regular wave loads on a fixed offshore oscillating water column-wave energy converter using CFD

Ahmed Elhanafi ^{a , b , ∗}

^a National Centre for Maritime Engineering and Hydrodynamics, Australian Maritime College, University of Tasmania, Launceston, Tasmania 7250, Australia

^b Department of Naval Architecture and Marine Engineering, Alexandria University, Alexandria, Egypt

Received 24 June 2016; received in revised form 29 July 2016; accepted 2 August 2016
Available online 23 September 2016

Abstract
In this paper, hydrodynamic wave loads on an offshore stationary–floating oscillating water column (OWC) are investigated via a 2D and 3D computational fluid dynamics (CFD) modeling based on the RANS equations and the VOF surface capturing scheme. The CFD model is validated against previous experiments for nonlinear regular wave interactions with a surface-piercing stationary barge. Following the validation stage, the numerical model is modified to consider the pneumatic damping effect, and an extensive campaign of numerical tests is carried out to study the wave–OWC interactions for different wave periods, wave heights and pneumatic damping factors. It is found that the horizontal wave force is usually larger than the vertical one. Also, there a direct relationship between the pneumatic and hydrodynamic vertical forces with a maximum vertical force almost at the device natural frequency, whereas the pneumatic damping has a little effect on the horizontal force. Additionally, simulating the turbine damping with an orifice plate induces higher vertical loads than utilizing a slot opening. Furthermore, 3D modeling significantly escalates and declines the predicted hydrodynamic vertical and horizontal wave loads, respectively.

This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ).

Keywords: Offshore oscillating water column; OWC; Hydrodynamic wave loads; Numerical wave tank; CFD; 3D effects.